This invention relates to a device which enables an external drive means to be employed to activate a circulating pump of an absorption chiller, without substantial loss of operating vacuum, even during shut down of the chiller.
More specifically, this invention relates to a coupler and manifold assembly for use between an external drive means and a circulating pump of an absorption chiller, which coupler and manifold assembly is capable of maintaining a vacuum or series of vacuums under operating and static conditions, while circulating a fluid, usually water, in a closed system, for cooling and lubricating the pump as the pump is circulating a refrigerant, such as lithium bromide, through another closed system, under vacuum, in an absorption chiller.
Heretofore, it has been the practice in the industry to employ a hermatically sealed "wet rotor" designed drive means to activate the circulating pump, comprising a specially designed water cooled electric motor, whereby the cooling and lubricating water passes through the gap between the rotor and stator of the motor. There are problem, however, with the use of hermatically sealed drive means, including an unpredictable operating life, due to a variety of particulate contaminants in the water, including welding slag, corrosion products and dirt, which particles abrade the thin stainless steel liner that separates the water from the stator windings. Additionally, the hermatically sealed drive means are not rebuildable, thus constituting a very expensive operational cost.
During operation, the rotor of the hermatically sealed drive means is spinning at approximately 1500-2000 RPMs, and cooling water is passed through the gap between the rotor and the stator at approximately 2 gallons per minute. Thereby, erosion of this liner also occurs due to the high velocity of the water as it passes through the thin space between the stator and the spinning rotor.
Mechanical stress is a third cause of failures of hermatically sealed drive means, especially during start-up when the pressure of the water in the drive means can very from as low as 7 mm of Hg absolute to 5 psi. This stress reversal fatigues the thin stainless steel liner and causes cracks which allow air to pass from the stator into the drive means. Upon failure, and passage of air into the drive means, the necessary vacuums for operating the absorption chiller are thus deteriorated and the efficiency of the system diminishes.
Up to the present time, the only solution for correcting the above problems, is to replace the hermatically sealed drive means at a great expense and without any guarantee for longevity of its repalcement, since the latter also has a small space between the stator and the rotor and the system is still circulating fluid with particulate contaminants therein.